Method and apparatus for forming flared tube ends

Abstract

A method for forming a flare in the end of a flexible tube comprises heating the end of the flexible tube to a near-melted state, inserting the end of the flexible tube into a flare-forming die with a flare forming portion, and pressing a mandrel into the end of the flexible tube, thereby pressure forming a flare in the end of the flexible tube.

What is claimed is: 
     
       1. A method for forming a flare in an end of a flexible tube, comprising:
 heating the end of the flexible tube to a near-melted state by direct contact with a contacting surface of a contact heating structure around an entire circumference of the tube end, said heating comprising inserting the end of the flexible tube into a receptacle of the contact heating structure to bring the tube end into direct contact with an inner surface of the receptacle, and wherein only the tube end is heated, and a remainder of the flexible tube remains unheated; 
 removing the end of the flexible tube from the contact heating structure; 
 inserting the heated end of the flexible tube into a flare-forming die, the flare forming die comprising a flare forming portion; 
 holding the heated end of the flexible tube in place in the flare-forming die by clamping an unheated portion of the flexible tube adjacent the heated end; 
 pressing a mandrel into the end of the flexible tube, thereby pressure forming a flare in the end of the flexible tube. 
 
     
     
       2. The method of  claim 1 , wherein the heating the end of the flexible tube to a near-melted state comprises contact heating the end uniformly around its circumference. 
     
     
       3. The method of  claim 1 , wherein the heating the end of the flexible tube to a near melted state comprises heating the end of the tube for a period of at least about thirty seconds. 
     
     
       4. The method of  claim 1 , comprising:
 providing a heater comprising a plurality of contact heating receptacles, each of the receptacles configured for receiving and heating ends of tubes of a diameter different from others of the plurality of receptacles; and 
 inserting the end of the tube into one of the plurality of contact heating receptacles. 
 
     
     
       5. The method of  claim 1 , comprising inserting the end of the flexible tube into the flare-forming die up to a tube stop. 
     
     
       6. The method of  claim 5 , wherein the tube stop comprises a transitional slope of the mandrel. 
     
     
       7. The method of  claim 1 , comprising:
 pressing the mandrel into the end of the flexible tube up to a flare forming position, to form a final form of a flare in the end of the flexible tube in one pressure forming action. 
 
     
     
       8. The method of  claim 7 , comprising:
 leaving the mandrel in the flare forming position for a time sufficient to form a flare that will retain a flared shape. 
 
     
     
       9. The method of  claim 7 , comprising:
 leaving the mandrel in the flare forming position for at least about sixty seconds. 
 
     
     
       10. The method of  claim 1 , comprising:
 pressure forming a flare in the end of the flexible tube, wherein an inner profile of the flare matches an outer profile of a fitting adapted to be fitted to the end of the flexible tube. 
 
     
     
       11. The method of  claim 1 , wherein the flare formed in the end of the tube has an inner flare profile which matches an outer flare profile. 
     
     
       12. The method of  claim 1 , wherein the flare formed in the end of the tube has a tube thickness which is reduced from a preformed tube thickness. 
     
     
       13. The method of  claim 1 , wherein the flexible tube comprises one of PFA, PVDF or FEP. 
     
     
       14. The method of  claim 1 , wherein said contacting surface is fabricated of a material selected to prevent the tube end from sticking to said surface and prevent contamination of the tube. 
     
     
       15. A method for forming a flare in an end of a flexible tube, comprising:
 heating the end of the flexible tube to a near-melted state by direct contact of an entire circumference of the tube end with a contact heating surface, said heating comprising inserting the end of the flexible tube into a receptacle of the contact heating structure to bring the tube end into direct contact with an inner surface of the receptacle, and wherein only the tube end is heated, and a remainder of the flexible tube remains unheated; 
 placing the heated end into a first portion of a tube receptacle in a first portion of a flare forming die; 
 bringing a second portion of the tube receptacle in a second portion of the flare forming die into a flare forming position, thereby clamping the tube in a clamping portion of the tube receptacle; 
 pressing a mandrel into the end of the flexible tube; 
 pressure forming a flare in the end of the flexible tube for a period of time sufficient to cool the end of the tube to a desired temperature; 
 withdrawing the mandrel and separating the first portion of the flare forming die from the second portion of the flare forming die; and 
 removing the end of the tube from the flare forming die. 
 
     
     
       16. A method for forming a flare in an end of a flexible tube, comprising:
 heating the end of the flexible tube to a near-melted state by direct contact with a contacting surface of a contact heating structure around an entire circumference of the tube end, said heating comprising inserting the end of the flexible tube into a receptacle of the contact heating structure to bring the tube end into direct contact with an inner surface of the receptacle, and wherein a remainder of the flexible tube remains unheated; 
 removing the end of the flexible tube from the contact heating structure; 
 inserting the heated end of the flexible tube into a flare-forming die, the flare forming die comprising a flare forming portion; 
 holding the heated end of the flexible tube in place in the flare-forming die by clamping an unheated portion of the flexible tube adjacent the heated end; 
 pressing a mandrel into the end of the flexible tube, thereby pressure forming a flare in the end of the flexible tube. 
 
     
     
       17. A method for forming a flare in an end of a flexible tube, comprising:
 heating the end of the flexible tube to a near-melted state by direct contact with a contacting surface of a contact heating structure around an entire circumference of the tube end, said heating comprising inserting the end of the flexible tube into a receptacle of the contact heating structure to bring the tube end into direct contact with an inner surface of the receptacle, and wherein only the inserted end is contact heated, and a remainder of the flexible tube remains unheated; 
 removing the end of the flexible tube from the contact heating structure; 
 inserting the heated end of the flexible tube into a flare-forming die, the flare forming die comprising a flare forming portion; 
 holding the heated end of the flexible tube in place in the flare-forming die by clamping an unheated portion of the flexible tube adjacent the heated end; 
 pressing a mandrel into the end of the flexible tube, thereby pressure forming a flare in the end of the flexible tube.